Mold for the manufacture of a plastic rope connector

ABSTRACT

This disclosure concerns a method for forming a plastic, buttonlike connector for securing a pair of crossed ropes together and also a mold for effecting the operation. The injection molding operation includes the step of holding the ropes in position in the mold cavity while the plastic is being injected thereinto and also a restricted opening where the ropes extend from the cavity to prevent loss of plastic during the injection operation.

States atent Maguire et al.

MOLD FOR THE MANUFACTURE OF A PLASTIC ROPE CONNECTOR Inventors: JohnMaguire; Jonathan E. Sharp; .Richard II. Frost, all of Littleton,

Colo.

Assignee: Rose Manufacturing Company,

Denver, Colo.

Filed: Oct. 21, 1970 Appl. No.: 82,693

Related U.S. Application Data Continuation of Ser. No. 847,884, Aug. 6,I969, Pat, No. 3,59l,2l5.

U.S. Cl. ..425/129, 425/444, 249/95 Int. Cl. B29f 1/10, B29f l/l4 Fieldof Search...l8/30 E, 30 UM, 30 WC, 30

18/30 WP, 30 NM, 2 RP, 42 D, 36, DIG. 59, DIG, 38; 264/263, 251; 249/67,68, 91, 95; 425/129, DIG. 802, 111, 444

References Cited UNITED STATES PATENTS 9/l97l Bramlcy et al ..264/25l X1 Mar. 27, 1973 2,920,354 1/1960 Zumbrunnen ..264/328 X 3,444,618 5/1969Sorlie ..l8/36 X 3,009,578 ll/l96l Foote et al... ....l8/36 X 3,313,8754/1967 Magerle 418/36 X 2,747,226 5/1956 Schnitzius et al.. ...l8/30 NM2,967,795 l/l96l Bollmeter et al. ....264/328 X FOREIGN PATENTS ORAPPLICATIONS 1,266,487 4/1968 Germany ..l8/30 UM Primary ExaminerJ.Spencer Overholser Assistant Examiner-David S. Safran AttorneyVanValkenburgh & Lowe [57] ABSTRACT This disclosure concerns a method forforming a plastic, button-like connector for securing a pair of crossedropes together and also a mold for effecting the operation. Theinjection molding operation includes the step of holding the ropes inposition in the mold cavity while the plastic is being injectedthereinto and also a restricted opening where the ropes extend from thecavity to prevent loss of plastic during the injection operation.

6 Claims, 11 Drawing Figures PATErHFEMAmmn 3 7 3,9 5

sum 2 UP 2 INVENTORS I Jonathan E.Sharp I Richard H. Frost John MaguireATTORNEYS MOLD FOR THE MANUFACTURE OF A PLASTIC ROPE CONNECTOR Thisapplication is a division of our copending application, Ser. No. 847,884filed Aug. 6, 1969, now U.S. Pat. No. 3,591,215.

This invention relates to rope connectors and more particularly toconnectors for securing crossed ropes. As such, the invention, animproved rope connector and hereinafter referred to as a rope connectoror simply a connector, is useful in the manufacture of rope nets, ropeladders and the like.

There is a continual increasing demand for compara-.

tively heavy rope nets, that is, for nets manufactured with and inchsize ropes or larger, for safety nets for hauling cargo and for similarpurposes. There is also a need to reduce the cost forthese comparativelylarge rope nets. Initially, such nets have been manufactured by handweaving, with heavy and cumbersome shuttles. It is simply not practicalto weave a net with such large ropes, either manually or by machine.Accordingly, it has been proposed to manufacture rope nets byinterlocking crossed ropes, spaced apart in an arrangement similar to awarp and a woof of a weave. Various clips and clamps prepared ahead oftime have been proposed for this purpose, but have not proven to beespecially successful. There is a need for an improved rope connectorfor the manufacture of rope nets which has a high holding strength,which is economical and -which iseasy to apply to crossed ropes.

The present invention was conceived and developed with the foregoingconsiderations in view, and comprises, in essence, a connector of aselected thermoplastic, synthetic resin formed by injection moldingabout a pair of crossed ropes. Preferably, the form of the connector issuch as to attain a maximum degree of strength with the minimum amountof material.

An object of the invention is to provide a novel and improved ropeconnector of a selected thermoplastic synthetic resin forinterconnecting crossed ropes, which has substantial strength andtoughness, which grips the ropes tightly and which is especially suitedfor the manufacture of rope nets.

Another object of the invention is to provide a novel and improved ropeconnector which can be quickly and easily applied to crossed ropes tosimplify the manufacture of heavy rope nets.

Another object of the invention is to provide a novel and improved ropeconnector which may be effectively used with various types of ropes, andmanufactured from a variety of easily obtainable materials, as alowcost, neat-appearing, compact, rugged and durable unit.

Another object of the invention is to provide a unique and simplifiedmethod for the injection molding of a connector about a pair of crossedropes which insures the gripping and holding of the crossed ropes inposition during the injection operation to properly fit the connectorupon the ropes, in a symmetrical, uniform manner.

Other objects of the invention are to provide a novel and improved moldform for the injection molding of a thermoplastic resin connector abouta pair of crossed ropes which permits the ropes to be quickly and easilyaligned within the mold, which thereafter holds the ropes in positionagainst the forces encountered during injection of hot plastic resininto the mold, and which provides for a subsequent, quick cooling of theresin to prevent possible damage to the rope by the hot resin.

With the foregoing and other objects in view, the present inventioncomprises certain constructions, combinations and arrangements of partsand elements and selected operations, sequences" and steps ashereinafter described, defined in the appended claims and illustrated inthe accompanying drawing in which:

FIG. 1 is a fragmentary perspective view of a net spanning an opening toillustrate one manner in which a net manufactured in accordance with theinvention may be used.

FIG. 2 is a plan view of a preferred embodiment of an improved connectorformed about a pair of crossed ropes.

FIG. 3 is a side elevation view of the connector and ropes shown at FIG.2.

FIG. 4 is a sectional elevation view through the connector as taken fromthe indicated line 4-4 at FIG. 2.

FIG. 5 is a sectional auiriliary view through the connector as takenfrom the indicated line 55 at FIG. 2.

FIG. 6 is a sectional elevation view of a two-piece mold for themanufacture of the connector by injection molding, with the mold blocksbeing closed together, the sectional view being taken through a centraltransverse plane of the mold which is at the same location as thesection shown at FIG. 4, but with some portions of the mold being shownin broken lines and with portions being broken away to showconstructions otherwise hidden from view.

FIG. 7 is a plane view of one face of the mold as taken from the partingline of the mold in the direction of the indicated arrows 77 at FIG. 6.

FIG. 8 is a plan view of the opposite face of the mold as taken from theparting line of the mold in the direction of the indicated arrows8--8-at FIG. 6.

FIG. 9 is a plan view of a connector similar to FIG. 2, but showing analternate embodiment incorporating the principles of the invention.

FIG. 10 is a sectional elevation view through the connector illustratedat FIG. 9, as taken from the indicated line l0l0 at FIG. 9.

FIG. 11 is a plan view of a connector similar to FIG. 2, but showinganother alternate embodiment of the invention wherein the ropes arecrossed at an inclination as to provide for a diamond-shaped netarrangement.

The present invention concerns the joining of two crossed ropes by aconnector of thermoplastic resin which is formed about the ropes by aninjection molding operation. The invention permits rope nets to bemanufactured in a simple manner, and is especially usefulfor themanufacture of comparatively heavy rope nets, formed by %-inch, %-inchand even larger ropes.

To exemplify the use of such a net, FIG. 1 illustrates, somewhatdiagrammatically, a portion of the entrance of a vertical shaft S,having a safety net N secured thereover, as by anchor hooks I-I holdingthe edges of the net about the sides of the shaft. The net, when used toprevent a person from falling into the shaft, is made of at least36-inch rope with the mesh spacing being 6- inches or less.

Consonant with the present invention, the net N is manufactured bycrossing spaced longitudinal ropes 20 and spaced transverse ropes 21, sodesignated as a matter of convenience, and with the ropes at eachcrossing being secured together by connectors C having the general formof a button as illustrated at FIG; 2.

The connector C is preferably formed of one of several types ofthermoplastic, synthetic resins, hereinafter called Plastics, which arecapable of being melted and molded to shape under the influence of heatand pressure. For example, suitable thermoplastic plastics havingvarious melting points include: polystyrene m.p. 250-400 F.;polyethylene m.p. 300-450 F.; polypropylene m.p. 340-450 F.; nylon m.p.440-600 F. Also such plastics can be blended with various fillers andreinforcing materials such as fiberglass, to improve the resistance toultra violet light and to increase the strength of the material. Anothergroup of plastics which may also be used for the manufacture of aconnector include thermosetting types of plastics, for example, varioustypes of polyester and polysulphide epoxy compounds.

One preferred plastic is polyethylene because it can be melted at acomparatively low temperature, has excellent molding qualities, and isvery tough and somewhat elastic, being able to withstand considerableabuse, such as the stretching and pulling of the ropes without tearingor breaking. Moreover, polyethylene can be specified as a high density,medium density or low density material to obtain selected variations inits physical properties, a high density or medium density polyethylenebeing preferable for rope connectors disclosed herein.

The connector C is capable of being used with several different types ofrope, such as ropes of manila, cotton and various types of plastics suchas rayon, polypropylene and drawn nylon. However, in connection with theplastic ropes, it is to be noted that the connector is formed by a hot,melted plastic flowing about the rope in a mold and it may becomeimportant to select a connector material which will not melt orotherwise damage the strands of the ropes. On the other hand, theopposite result may be desired, that is to provide sufficient heat as toessentially weld the connector to the rope. Simple tests can determinewhether or not a plastic of a selected type, suitable in other respects,can be used with a given rope.

The preferred type of connector C, illustrated at FIGS. 2 to 5, is inthe form ofa circular button holding a pair of crossed ropes 20 and 21,having a diameter, preferably between three and four times the ropesize, a maximum thickness of about twice the rope size and beinggenerally symmetrical about a polar axis, normal to the plane of theropes. As a matter of convenience, the following description will referto the face of the connector shown at FIG. 2 as being the upper face,although it is recognized that in use, the connector may be oriented inany desired manner.

This connector is formed as a pair of tubular, crossed sheaths tightlyembracing the ropes, an upper sheath 22 holding the longitudinal rope 20and a lower sheath 23 holding the transverse rope 21. These sheathsmerge at the center of the connector with the crossed ropes within thembeing tightly squeezed together as at 24, FIG. 4, to minimize thethickness of the connector.

Each outward end of each sheath, 22 and 23, ter-- minates as a circularflange 25 having its outer wall 26 arcuate to form a portion of thecircular, peripheral edge of the connector. These flanges are orientedto be centered at a common level, at a central plane through theconnector normal to the polar axis thereof, with the ropes extendingfrom each flange at a centered position I so that the axes of all ropeportions extending from-the connector lie in the common central plane.Accordingly, theportion of each rope 20 and 21 within the connector, isarched as an offset to accommodate the other rope at the common crossingpoint, at the center of the connector, as in the manner illustrated atFIG. 4. At the same time, the outward edge of each sheath 22 and 23 isarched, as at 27 and 28 respectively, to permit each sheath to betterembrace the'portions of the ropes 20 and 21 within the connector.

The crossed flanged sheaths 22 and 23, in the shaped of a cruciform, arefurther reinforced and rigidified by arcuate rims 29 between theadjacent edges of adjacent flanges 25 to complete the circular, outerwall of the connector as illustrated. The pie-like spaces between thecrotches of the crossed sheaths and these arcuate rims are enclosed bycomparatively thin fillets 30, at the central plane of the connector, toprovide a continuity of structure.

This connector C includes four passageways 31, one at each crotch of thecruciform shaped sheathsand these passageways are formed by retainingpins, hereinafter described. The connector also includes a shallow basesocket 32 in the lower sheath v23 at the axis of the connector. Tocomplete the unit thus described, a rosette mark 33 will appear at thetop of the uppersheath 22, opposite the socket 32, which is a disruptionresulting from the action of an injection nozzle at the wall of the moldwherein the connector is formed. I

FIG. 6-8 illustrate a mold for forming the connector C upon a pair ofcrossed ropes. Injection molding apparatus capable of retaining the moldto move the mold section together and apart is conventional and need notbe described. In the manufacture of a rope net, it is contemplated thatthe longitudinal and transverse ropes will be properly spaced apart on asuitable frame, and that the frame and the injection apparatus will beshiftable with respect to each other with suitable indexing controls toposition the mold at each rope crossing point to form a connector, allin any suitable sequence of shifting operations.

The mold is formed as two half sections: a feed section and a backingsection 51, so designated because of the location of an injection nozzle52 in the feed section which enters the mold cavity at its center toform the rosette 33 heretofore described. This rosette is formed becausea cross-like configuration of the nozzle exit is provided in lieu of asimple orifice to prevent a rope strand fromaccidentally blocking offthe flow of' plastic into the mold. These sections are separable atasuitable parting plane P, preferably at a central plane of theconnector and move together and'apart by conventional means, not shown.Also, other features of these mold sections are conventional. Forexample, each section may include cooling passageways 53 to carry acoolant liquid to reduce the setting time ofa hot plastic materialinjected into the mold cavity. The backing section may include suitableguide pins 54 on the face plane of that section and the feed section mayinclude mating sockets 55 on its face plane to assure properregistration of the mold sections when they come together.

The mold cavity is in the general form of the connector, having an uppersheath portion 220, a lower sheath portion 23a, flange portions 25a,arcuate rim portions 290, and spaces 30a to form the fillets 30. Askilled die maker can form these features of the mold cavity, and willpreferably form the cavity portions in each section 50 and 51 in abalance manner with the parting plane P at the center plane of theconnector as illustrated.

A unique feature in high pressure injection molding resides in thepassing of crossed ropes through the mold in order to inject the connectabout them. Accordingly,

passageways 56 extend from the mold cavity to each side of the mold,with each mold section 50 and 51 forming a half of'the passageway. Toprevent leakage of plastic from the mold cavity through thesepassageways, a gate ring 57 is located in each passageway adjacent toeach flange portion 25a of the mold cavity which is sized to squeeze therope extending through the passageway with sufficient tightness as toprevent flow therepast, but not so tight as to cut or otherwise damagethe rope. Each gate ring 57 is formed as two half ring portions with aring portion being at each mold section 50 and 51.

To hold the crossed ropes and 21 across the mold cavity and in positionwithin the mold while the hot, viscous plastic is being injected intothe mold cavity, four finger-like restraining pins 58 are mounted uponthe backing section 51 to extend across the cavity parallel with thepolar axis thereof. These restraining pins hold the crossed ropes ateach crotch of the cross and prevent sidewise movement of the ropes.When the sections 50 and 51 are closed together, the pins 58 ex tendinto sockets 59 in the feed section 50 of the mold. Accordingly, theyform the passageways 31 through the connector C as heretofore described.As such, they may be tapered slightly to facilitate removing theconnector from the mold after it is formed.

The force of viscous plastic injected from the nozzle 52 is substantialand is sufficient to push the ropes against the opposite wall of themold cavity in the backing section 51. Accordingly, a spacer pin 60 isprovided at the center of the mold cavity opposite the nozzle 52 whichprotrudes a short distance into the sheath portion 23a of the moldcavity to contact and abut against the transverse rope section 21 whenit is placed into the mold cavity. This forms the socket 32 in thefinished connector.

The spacer pin 60 is also used to remove a finished connector from themold after it has been formed upon a pair of crossed ropes and cooledand after the mold cavities 50 and 51 move apart. This pin 60 is ideallysuited for an ejector since it is at the polar axis of the connector. Toperform this ejection function, the connector pin is extended through anaxially centered passageway 61 in the backing section 51 to function asa piston rod and terminate as a piston 62 in a hydraulic cylinder 63carried upon the backing section 51. The piston 62 actuates within thecylinder 63 to extend the spacer pin 60 outwardly and across the moldcavity as a single complete ejection movement, the length of the pinbeing sufficient to push the finished connector off the retaining pins58 so that it may be easily removed from the mold. Suitable hydrauliclines extend from a regulator pressure source to the cylinder in anymanner to extend and retract this spacer pin 60, the lines not beingshown in the drawing because the same may be an entirely conventional,well known arrangement for extending and retracting a rod such as thespacer pin 60. It is apparent that the pin may also be arranged to ejectwith a suitable mechanical linkage instead of the hydraulic mechanismshown.

In operating the mold to manufacture a connector C upon a pair ofcrossed ropes, the mold sections 50 and 51 are initially separated andthe crossed ropes 20 and 21 are located between the mold sections withthe transverse rope 21 being at the side of the backing section 51.First, the transverse rope 21 is placed in position against the backingsection 51, with the rope lying in the proper passageways 56 and placedbetween the two sets of pins 58. Next, the longitudinal rope section 20is placed in position against the backing section of the mold 51 and inits passageways and between the two sets of pins 58 crosswise from therope 21. Next, the mold cavity is closed and injection of hot fluidplastic commences. Restrained, as above described by the pins 58 and thespacer pin 60, the plastic flows evenly about the ropes to form theconnector.

After the connector is completed and cooled, the mold sections movedapart. The connector is secured to the restraining pins 58 and thusremains with the backing section 51. Extension of the spacer pin 60moves the connector off the pins, and the apparatus is ready for anothercycle of operation.

FIGS. 9 and 10 illustrate a connector of a more simplified form, thatis, in the general form of a flat, oblate spheroid 70. The longitudinaland transverse ropes 20 and 21 extend through the spheroid as heretoforedescribed.

Although the sheath forms about the ropes are eliminated by using thebulky spheroid shape, it is still necessary to retain the ropes inposition and accordingly, the passageways 31' and the socket 32' at thepole of the spheroid, will be formed in the modified connector, using amold similar to that heretofore described, the spheroid being bounded bya circular wall 26 from whence the rope portions extend. Also, therosette 33 will appear on the pole opposite the socket 32'.

FIG. 11 illustrates a connector which is modified by inclining the ropesat an angle to provide for a diamond-shaped net or the like. This unitprovides for an elliptically shaped connector with the wall 26" beingrounded to an elliptical form, but is otherwise substantially the sameas the connector shown at FIG. 2, having an upper sheath 22" and lowersheath 23" terminated by flanges 25". The flanges are connected byarcuate rims 29" with the gaps closed by fillets 30" as aforedescribed.The structure includes passageways 3]", a socket 32" which is not shown,and a rosette mark 33' on the upper face of the unit.

We have now described our invention in considerable detail. However, itis obvious that others skilled in the art can build and devise alternateand equivalent constructions which are nevertheless within the spiritand scope of our invention. Hence, we desire that our protection belimited not by the constructions illustrated and described, but only bythe proper scope of the appended claims.

We claim:

1. An injection mold to form a connector of synthetic resin plasticabout a pair of crossed ropes, said connector being characterized byhaving a sheath embracing each rope, with each sheath merging into theother at the center of the connector where the ropes cross, andincluding: i

a. a pair of opposing surface members adapted to move together to aselect registration with their contacting surfaces defining the partingof the mold and with a portion of the mold cavity being formed in eachmember;

b. channels in the surfaces. of each member forming passageways when themembers are moved together to receive the pair of crossed ropes andpermit the ropes to extend into and cross within the mold cavity; Y

c. an injection nozzle means in one member at the center of the moldcavity where the ropes cross each other;

d. an abutment pin in the other member at the center of the mold cavityopposite the injection nozzle means, and extended into the mold cavityto hold a pair of crossed ropes therein in position against the pressureof plastic being injected into the cavity through the nozzle; and

e. a plurality of restraining pins disposed within the said mold cavityand arranged perpendicular to said contacting surfaces, said restrainingpins being located at the intersection of lines extended along the sidesof the channels and across the mold cavity, whereby said ropes are heldin a center position in the mold cavity and against the abutment pinwhen plastic is injected into the mold cavity.

2. In the organization set forth in claim 1, wherein:

said restraining pins and the abutment pin are mounted in the samemember;

said abutment pin is shiftably carried in said member;

and

means adapted to extend the abutment pin from its normal position in themold cavity to a position therebeyond to remove a completed connectorfrom the mold cavity and from the aforesaid restraining pins when themembers are separated.

3. In the organization set forth in claim 1, including pressure rings ineach passageway adjacent to the mold cavity adapted to tightly grip arope therein, to prevent loss of plastic through the passageway whenplastic is being injected into the cavity.

4. In the organization set forth in claim 1, wherein the nozzle exitinto the mold cavity is divided into sections to prevent a rope portionwithin the cavity from closing off the exit.

5. A mold having an internal cavity for forming a connector around aplurality of crossed, elongated members, the mold comprising:

a. at least two sections separable along connecting surfaces whichdefine a parting plane and a portion of said cavity being formed in eachof said sections;

b. means for injecting hardenable material into said cavity for moldingsaid connector;

0. a plurality of crossing passageways formed in said contactingsurfaces and extending diagonally across said mold cavity; a d. saidpassageways being arranged to correspond with the desired position ofsaid elongated members and sized to fit said members;

e. a plurality of restraining pins disposed within said mold cavity andarranged perpendicular to said contacting surfaces; and

f. said restraining pins being located at the intersection of linesextended along the sides of adjacent passageways so as to retain saidelongated members in a centered position in the cavity when thehardenable material is injected into the mold cavi ty. v

6. In the organization set forth in claim 5, further including:

means for supporting said crossed elongated members in a directionperpendicular to said contacting surfaces;

said supporting means including an abutment pin extending from one ofsaid sections, centrally located within said cavity and perpendicular tosaid contacting surfaces so as to prevent movement of said crossedmembers when the hardenable material is injected into the cavity.

1. An injection mold to form a connector of synthetic resin plasticabout a pair of crossed ropes, said connector being characterized byhaving a sheath embracing each rope, with each sheath merging into theother at the center of the connector where the ropes cross, andincluding: a. a pair of opposing surface members adapted to movetogether to a select registration with their contacting surfacesdefining the parting of the mold and with a portion of the mold cavitybeing formed in each member; b. channels in the surfaces of each memberforming passageways when the members are moved together to receive thepair of crossed ropes and permit the ropes to extend into and crosswithin the mold cavity; c. an injection nozzle means in one member atthe center of the mold cavity where the ropes cross each other; d. anabutment pin in the other member at the center of the mold cavityopposite the injection nozzle means, and extended into the mold cavityto hold a pair of crossed ropes therein in position against the pressureof plastic being injected into the cavity through the nozzle; and e. aplurality of restraining pins disposed within the said mold cavity andarranged perpendicular to said contacting surfaces, said restrainingpins being located at the intersection of lines extended along the sidesof the channels and across the mold cavity, whereby said ropes are heldin a center position in the mold cavity and against the abutment pinwhen plastic is injected into the mold cavity.
 2. In the organizationset forth in claim 1, wherein: said restraining pins and the abutmentpin are mounted in the same member; said abutment pin is shiftablycarried in said member; and means adapted to extend the abutment pinfrom its normal position in the mold cavity to a position therebeyond toremove a completed connector from the mold cavity and from the aforesaidrestraining pins when the members are separated.
 3. In the organizationset forth in claim 1, including pressure rings in each passagewayadjacent to the mold cavity adapted to tightly grip a rope therein, toprevent loss of plastic through the passageway when plastic is beinginjected into the cavity.
 4. In the organization set forth in claim 1,wherein the nozzle exit into the mold cavity is divided into sectioNs toprevent a rope portion within the cavity from closing off the exit.
 5. Amold having an internal cavity for forming a connector around aplurality of crossed, elongated members, the mold comprising: a. atleast two sections separable along connecting surfaces which define aparting plane and a portion of said cavity being formed in each of saidsections; b. means for injecting hardenable material into said cavityfor molding said connector; c. a plurality of crossing passagewaysformed in said contacting surfaces and extending diagonally across saidmold cavity; d. said passageways being arranged to correspond with thedesired position of said elongated members and sized to fit saidmembers; e. a plurality of restraining pins disposed within said moldcavity and arranged perpendicular to said contacting surfaces; and f.said restraining pins being located at the intersection of linesextended along the sides of adjacent passageways so as to retain saidelongated members in a centered position in the cavity when thehardenable material is injected into the mold cavity.
 6. In theorganization set forth in claim 5, further including: means forsupporting said crossed elongated members in a direction perpendicularto said contacting surfaces; said supporting means including an abutmentpin extending from one of said sections, centrally located within saidcavity and perpendicular to said contacting surfaces so as to preventmovement of said crossed members when the hardenable material isinjected into the cavity.